The agreement between theory and the experimental \(z_h\)  spectrum is quite remarkable, given that it spans some 2 orders of magnitude, which suggests that at these kinematics a leading power perturbative QCD factorization at next-to-leading order provides sufficient accuracy to describe the data.
Interestingly, the differences between the multiplicities for positively and negatively charged hadron species increase with \(x_{\mbox{\tiny \rm Bj}}\) , especially for kaons, and in the valence region these can differ by an order of magnitude for low values of \(Q^2\) .
Such differences can enhance our ability to extract flavor dependent effects in nonperturbative PDFs and parton to kaon FFs from the data.
The new data set included for the first time in the present JAM analysis, namely the unidentified charged hadron data shown in Fig. REF , are also well described by our nonperturbative ansatz for the corresponding FFs.
In contrast to the excellent agreement with the \(z_h\)  dependence of the data in Figs. REF –REF , we note that analysis of the same data differential in the hadron transverse momentum using existing PDFs and FFs within TMD factorization results in poor agreement between predictions and data [1]}, [2]}, indicating that further work is needed to understand the SIDIS transverse momentum spectra.
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